The present invention relates to a theft deterrent method and system and more particularly to a tamper-resistant theft deterrent method or system that can be used to protect different kinds of property.
A conventional vehicle anti-theft system interprets the breaking of a vehicle window or an unauthorized key manipulation as an attempt to steal the vehicle. The system reacts by sending a theft alarm signal to a monitoring agency, such as a security company or a property management company. The monitoring agency may send its own vehicles to investigate and/or may notify the local police that an attempted theft is in progress.
The prior also teaches that an anti-theft system of the type described above may be enhanced by the use of a system that can disable the vehicle by transmitting a specific type of radio signal to the vehicle from a remote security agency.
One problem with a conventional vehicle anti-theft system is that the thief can disable the system by disabling the radio transmitter used to send a theft alarm signal to the monitoring agency. A number of options are open to the thief. The thief may cut the wires to the antenna, break the antenna, smash the radio transmitter or transmit a jamming radio wave. If the monitoring agency never receives the theft alarm signal, it has no way of knowing that the theft has occurred.
A thief can similarly defeat the type of system which relies on a disabling signal from a remote security agency by breaking or removing the receiving antenna, cutting the electrical wires to the receiving antenna, transmitting a jamming signal, etc., to prevent the disabling signal from ever reaching the vehicle.
Given the relative ease with which existing anti-theft systems can be disabled, such systems have only a limited effect on a determined, knowledgeable thief.
Some of the problems with existing anti-theft systems might be solved by making the system components harder to break or by concealing components, such as the transmitting or receiving antennas and the wires leading to them. Such measures may slow down a thief but will probably not stop him and will almost certainly add to the costs of buying, installing and maintaining the system. Moreover, such measures will be completely ineffective against radio jamming signals.
Some thought has been given to concealing the anti-theft system so that the thief remains unaware of its existence and thus does not attempt to disable the system before stealing the vehicle. The problem with this idea is that it nullifies one of the supposed primary advantages of having an anti-theft system to begin with; namely, that a potential thief will be discouraged from attempting to steal vehicles which are known to be equipped with anti-theft systems.
The present invention overcomes the noted problems of the prior art systems using a system which is tamper-resistant and which need not remain concealed in order to remain effective. The system is one that can be used to protect a variety of property not just vehicles.
An anti-theft system constructed in accordance with the present invention receives a periodic enabling signal, referred to as a keep-alive signal, from a remote source. Each received keep-alive signal restarts a run period; that is a period of time during which the protected property will continue to operate normally. As long as a keep-alive signal continues to be received before the current run period expires, normal operation continues without interruption. The agency responsible for providing the periodic keep-alive signals will stop sending those signals when it learns that an attempt is being made to steal the protected property. Once the current run period expires, steps are initiated to disable the property or to otherwise make it unattractive to the thief to continue the attempt to steal the property.
A thief who attempts to defeat a system of the type described by breaking, jamming or otherwise disabling the receiver of the keep-alive signals will only ensure that the anti-theft operations are initiated at the end of the current timeout period.